Sparknotes erroneously states in its Analysis — Act I, scenes i-iii (2nd Paragraph), “In Act I, scene iv, after Cyrano fights in a dramatic duel, his friend Cuigy wittily claims that Cyrano’s name is Dartagnan,” of The Three Musketeers fame.
What actually happens in Rostand’s play is this: an appreciative Musketeer, thoroughly entertained by the duel, commends Cyrano on his swordsmanship and then quickly leaves.
Cyrano asks Cuigy, “What was that gentleman’s name?”
Cuigy answers, “Oh…D’Artangnan.”Read more→

Sparknotes says in regards to the following quote "VALVERT: Your nose is . . . very big. CYRANO: Yes, very. VALVERT: Ha! CYRANO: Is that all?" that "Remembering the promise he made to Roxane to keep Christian safe, Cyrano responds to Valvert’s ridiculing of his nose with biting, ironic criticism instead of violence." At this point in time, Roxane has said nothing to Cyrano about Christian, and indeed, Cyrano kills Valvert upon the final line of his balade.

According to the Context Article, Edmond Rostand's first play was "Le Gant Rouge", but this conflicts with Wikipedia, because it states that Edmond Rostand's first play as "Les romanesques". This should be fixed immediately, because I can't decide which source is true.